It is desirable to be able to measure the rate of spread of a fire in forest or wildland areas, however the methods and equipment previously available were either inadequate for the task or too expensive for extensive measuring projects.
Current techniques for measuring rate of spread can be grouped into three classes: visual, mechanical, and electronic. Visual observations, either manual or photographic, are constrained by the requirements that the apparatus or observer see what is actually happening and to provide a safe position from which to observe. As for example, a random measuring system as is customarily used cannot be utilized in a burned area except in a low-intensity fire or a fire occuring within a small area because of the necessity that the point being observed be actually visible and also far enough away to be safe. Mechanical observations again require a safe vantage point and also have tended to require long set up times making the measurement of large fire areas very impractical. Electronic measurements are also possible using thermocouples and recording apparatus, however, previous electronic equipment proposed has had the extreme disadvantage of high cost, again limiting the areas that may be monitored thereby making routine and ongoing measuring programs very impractical.
Because a systematic survey of the rate of spread of forest fire requires equipment that can accommodate the highly variable characteristics of such fire, including the variable way in which such fires spread and the differences in local spread rates when compared to the spread rate of the fire as a whole. Also, the extreme heat that is associated with a forest fire has had the disadvantage of causing equipment malfunction and therefore requiring more expensive equipment in order to ensure the accuracy of measurements obtained.
Therefore, there is need for a low cost electronic method for measuring the rate of spread of forest fires and also for low cost equipment items that can be utilized in conjunction with such method.